This invention relates generally to golf club heads and to methods for making them and, more particularly, to golf club heads and related methods in which the club head incorporates an added weight component to provide the head with a desired weight.
One important parameter of golf clubs is the weight of their heads, which must be carefully controlled, not only to meet the particular needs of the individual golfer using the club, but also to combine with the golfer""s other clubs to form a matched set. Golf club manufacturers, therefore, customarily weigh each club head during the manufacturing process and add one or more components of precise weight so as to adjust the club head""s weight to a desired overall value.
The added components for adjusting the club head""s weight have taken many different forms. One common form, which has been used with metal wood-type golf club heads, is a material such as epoxy that is added in selected amounts to the club head""s hollow cavity. Although this use of epoxy has been generally effective in correcting for weight variances in golf club heads, negative side effects can result. For example, the epoxy can affix to the inner surface of the club head""s ball-striking face, which can have adverse effects, such as lowering the face""s coefficient of restitution. Also, pooling of the epoxy can displace the club""s center of gravity, and can affect the club head""s sound at ball impact, in an indeterminate way.
Another common form for the added weight component has been a metallic plug installed into the hollow shaft of the club, where it joins to the club head""s hosel. Although generally effective in providing the club head with the desired weight, such metallic plugs sometimes can loosen and cause undesired rattling during the club""s use. In addition, placement of such weights within the shaft can move the club head""s center of gravity to an undesired location. Further, if the need ever arises to replace the club""s shaft, the weight will necessarily be removed and an equivalent weight might not be installed in its place.
Yet another common form for the added weight component has been a plurality of metallic weights carried within correspondingly sized cavities formed in a housing that is secured, e.g., by screws, to a portion of the golf club head, typically the sole. Although generally effective in providing the club head with the desired weight, the process of assembling such weight components is considered to require excessive manufacturing effort and cost. Also, the housing and/or weight components sometimes can loosen during the club""s use.
It should therefore be appreciated that there is a need for an improved golf club head, and method for making it, in which the head""s weight can be tailored to a precisely selected value, without adversely affecting important parameters such as the club head""s coefficient of restitution or center of gravity, without being susceptible to loosening when the club is used or when the club""s shaft is removed or replaced, and without requiring excessive time and effort during manufacture. The present invention fulfills this need and provides further related advantages.
The present invention resides in an improved golf club head, and in a method for making it, in which the weight of the head is tailored to a precisely selected value without adversely affecting club head parameters such as coefficient of restitution or center of gravity, without being susceptible to loosening when the club head is used or when the associated shaft is removed or replaced, and without requiring excessive time and effort during manufacture. The golf club head includes a hollow main body having a sole, a crown, a heel, a toe, a ball-striking face, and a rear wall, with the heel defining a hosel for receiving the lower end of a shaft, and the rear wall defining a rear wall cavity for receiving a special weight cartridge. The hollow main body defines a central axis along which the head is intended to move when being used to strike a golf ball. The weight cartridge includes a polymeric housing having one or more elongated cavities for conformably receiving one or more weights. The rear wall cavity is substantially aligned with the central axis and is sized and configured to conformably and slidably receive the polymeric housing, along an axis substantially aligned with the central axis. The weight cartridge is secured within the rear wall cavity, in an installation position, without the need for a screw attachment.
The weight cartridge is selected from a plurality of weight cartridges, all having substantially the same size and shape, but each having a different weight. The particular weight cartridge is selected so that its weight will provide the golf club head with the desired total weight.
In its preferred form, the rear wall cavity has a substantially rectangular cross-section in planes perpendicular to the central axis, and spaced above the sole of the head. The weight cartridge is retained in its installation position within the rear wall cavity by a snap fit, and/or by an interference fit, and/or by a bonding material such as double-sided tape and/or epoxy. When a snap fit attachment is being used, the housing and cavity, together, include a cooperating ridge and groove structure.
The one or more weights preferably comprise material selected from the group consisting of polymers, aluminum, steel and tungsten. The cavities defined by the polymeric housing preferably are at least three in number, each cavity having an elongated, substantially cylindrical shape, and the plurality of weights each have a substantially cylindrical shape sized to fit snugly within these cavities. The plurality of weight cartridges have weights that range from about 3 g to about 16 g, which represents about 1.5% to about 8% of the golf club head""s total weight.
In yet further more detailed features of the invention, the polymeric housing has a top wall, a bottom wall, a front wall, left and right side walls, and a rear wall, and substantially only the rear wall of the housing is visible when the housing is located in its installation position. The cavities define by the polymeric housing open into a wall of the housing other than the rear wall, such that the weights are prevented from exiting the housing when the housing is located in its installation position. Preferably, the cavities open into the front wall of the housing, and they are oriented with their longitudinal axes substantially parallel with each other and with the club head""s central axis.
Other features and advantages of the invention should become apparent from the following description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.